Network design
The purpose of this page is to give an overview of the current design of the network of the Wikimedia servers, and to provide a place to develop a new and improved network scheme.
Overall system design
The folowing is the general system design plan which the network layer must efficiently accommodate.
- Databases in a central pool with each serving a subset of the wikis, so each has high cache efficiency and the total number needed to handle any query load is minimised. Database servers cost US$5,000-$8,000 each, depending on exact equipment.
- A central pair of old text database servers (part of the long term storage growth plan for the databases, to move this high volume and seldom accessed data off costly and comparatively small disk systems).
- Memcached caching spread on apaches across the whole cluster, producing one very large cache pool, accessible from any apache and stored on half or more of the apaches. Segmenting the pool would decrease the overall hit rate, increasing the number of apaches and database servers required for any given system load level.
- Load balancing of squids and apaches, currently expected to use two or three systems between the internet and the squids and the same set between the squids and the apaches.
A key network systems design requirement is efficient access from any apache to any apache running memcached (expected to be more than half of all apaches) and efficient access from any apache to any database server. Losing this capability would dramatically increase overall system cost.
Current situation
Wikimedia servers reside in two racks along with Bomis servers, hosted at Candidhosting. Wikimedia/Bomis have a dedicated IP range, 207.142.131.192/26. There are two gateways: 207.142.131.193 and 207.142.131.225. Total burstable bandwidth is 1000 Mbit/s, delivered through one optic fiber 1000base-SX link.
Wikimedia owns a Cisco C3560G-48TS switch, and three Netgear Gigabit switches.
